Enhancing the signal-to-noise ratio in ophthalmic optical coherence tomography by image registration--method and clinical examples.

Optical coherence tomography (OCT) has already proven an important clinical tool for imaging and diagnosing retinal diseases. Concerning the standard commercial ophthalmic OCT systems, speckle noise is a limiting factor with respect to resolving relevant retinal features. We demonstrate successful suppression of speckle noise from mutually aligning a series of in vivo OCT recordings obtained from the same retinal target using the Stratus system from Humphrey-Zeiss. Our registration technique is able to account for the axial movements experienced during recording as well as small transverse movements of the scan line from one scan to the next. The algorithm is based on a regularized shortest path formulation for a directed graph on a map formed by interimage (B-scan) correlations. The resulting image enhancement typically increases the contrast-to-noise ratio (CNR) with a factor of three or more and facilitates segmentation and quantitative characterization of pathologies. The method is currently successfully being applied by medical doctors in a number of specific retinal case studies.

[1]  M. Bashkansky,et al.  Statistics and reduction of speckle in optical coherence tomography. , 2000, Optics letters.

[2]  M. Larsen,et al.  Enhanced optical coherence tomography imaging by multiple scan averaging , 2005, British Journal of Ophthalmology.

[3]  J. Fujimoto,et al.  Enhanced visualization of macular pathology with the use of ultrahigh-resolution optical coherence tomography. , 2003, Archives of ophthalmology.

[4]  B. Bouma,et al.  Handbook of Optical Coherence Tomography , 2001 .

[5]  Carmen A Puliafito,et al.  Automated detection of retinal layer structures on optical coherence tomography images. , 2005, Optics express.

[6]  J. Fujimoto,et al.  Optical coherence tomography of the human retina. , 1995, Archives of ophthalmology.

[7]  Byeong Ha Lee,et al.  Advantages of Adaptive Speckle Filtering Prior to Application of Iterative Deconvolution Methods for Optical Coherent Tomography Imaging , 2005 .

[8]  Paul D. Hale,et al.  Alignment of noisy signals , 2001, IEEE Trans. Instrum. Meas..

[9]  Ramesh C. Jain,et al.  Using Dynamic Programming for Solving Variational Problems in Vision , 1990, IEEE Trans. Pattern Anal. Mach. Intell..

[10]  William E Smiddy,et al.  Photoreceptor layer features in eyes with closed macular holes: optical coherence tomography findings and correlation with visual outcomes. , 2005, American journal of ophthalmology.

[11]  J. Fujimoto,et al.  Speckle reduction in optical coherence tomography images by use of a spatially adaptive wavelet filter. , 2004, Optics letters.

[12]  B. Vakoc,et al.  Speckle Reduction in OCT using Massively-Parallel Detection and Frequency-Domain Ranging. , 2006, Optics express.

[13]  G. Ying,et al.  Effect of viagra on retinal vein diameter in AMD patients. , 2006, Experimental eye research.

[14]  T. Jørgensen,et al.  Normative data of outer photoreceptor layer thickness obtained by software image enhancing based on Stratus optical coherence tomography images , 2008, British Journal of Ophthalmology.

[15]  R. Bellman.  Dynamic programming. , 1957, Science.

[16]  Hiroshi Ishikawa,et al.  Retinal nerve fiber layer assessment using optical coherence tomography with active optic nerve head tracking. , 2006, Investigative ophthalmology & visual science.

[17]  Daniel L Marks,et al.  Speckle reduction by I-divergence regularization in optical coherence tomography. , 2005, Journal of the Optical Society of America. A, Optics, image science, and vision.

[18]  Fluorescein angiographic risk factors for progression of diabetic retinopathy. ETDRS report number 13. Early Treatment Diabetic Retinopathy Study Research Group. , 1991, Ophthalmology.

[19]  David Huang,et al.  Handbook of optical coherence tomography. , 2003, Ophthalmic surgery, lasers & imaging : the official journal of the International Society for Imaging in the Eye.

[20]  Grading diabetic retinopathy from stereoscopic color fundus photographs--an extension of the modified Airlie House classification. ETDRS report number 10. Early Treatment Diabetic Retinopathy Study Research Group. , 1991, Ophthalmology.

[21]  Thomas Martini Jørgensen,et al.  Enhanced optical coherence patterns of diabetic macular oedema and their correlation with the pathophysiology. , 2008, Acta ophthalmologica Scandinavica.

[22]  Peter K Kaiser,et al.  Optical coherence tomographic patterns of diabetic macular edema. , 2006, American journal of ophthalmology.

[23]  B. Pogue,et al.  Automated region detection based on the contrast-to-noise ratio in near-infrared tomography. , 2004, Applied optics.

[24]  M. Larsen,et al.  Diabetic macular oedema: a comparison of vitreous fluorometry, angiography, and retinopathy , 2002, The British journal of ophthalmology.

[25]  J. Schmitt,et al.  Speckle in optical coherence tomography. , 1999, Journal of biomedical optics.

[26]  L. Schmetterer,et al.  Intravenous administration of diphenhydramine reduces histamine-induced vasodilator effects in the retina and choroid. , 2006, Investigative ophthalmology & visual science.

[27]  F L Ferris,et al.  Photocoagulation for diabetic macular edema. , 1987, Archives of ophthalmology.

[28]  Delia Cabrera Fernandez,et al.  Delineating fluid-filled region boundaries in optical coherence tomography images of the retina , 2005, IEEE Transactions on Medical Imaging.

[29]  Michael Buckley,et al.  Regularised shortest-path extraction , 1997, Pattern Recognit. Lett..